MARS CLIMATE DATABASE v5.0 USER MANUAL - The Mars ...

3. With the installation of the minimal baseline MCD distribution, only the “climatology” dustscenario with an average Extreme UV solar input is provided (corresponding datafiles are inthe clim aveEUV subdirectory of the data directory). The other dust scenarios (clim minEUV,clim maxEUV, cold, warm, strm) are provided separatly and should likewise be addedas subdirectories in the data directory. A full installation (all 8 scenarios) of the MCD takesabout 8.5 Gb of disk space.4. In the working directory (e.g. mars) it is convenient to set up a MCD DATA symbolic link 2in the same directory to point to the data directory, wherever it has been stored:ln -s /full/path/to/mcd/data MCD DATAN.B In the call mcd subroutine , the path to the directory can be given as an input using thedset argument (e.g. dset=’/full/path/to/mcd/data/’) although by default thesubroutine will use MCD DATA/ if dset is not initialized or set to ’ ’.5. If NetCDF is not available on your system, you must install the NetCDF library following theinstructions given on their www site (see above). For this purpose, you have the choice eitherto build and install the NetCDF package from source, or use prebuilt binary releases if theyare available for your platform (check the ”Frequently Asked Question”).Ideally, you can install the full NetCDF package as recommanded on the web site. In practice,the minimum you need to run the access software are only two files : an include file namednetcdf.inc and a Fortran library file named libnetcdf.a. The version of the filesdepends of the machine and of the compiler. An easy way to get them is to go to the unidatanetcdf web page, click on precompiled binaries, download a compressed file corresponding toyour operating system, uncompress the file. You’ll find the netcdf.inc in the includedirectory, and the libnetcdf.a in the lib directory. You’ll need to provide the path tothese two files when compiling applications (see the compile files in the database). Unfortunately,this does not always work : if your compiler doesn’t work with the precompiledlibrary, you will have to recompile Netcdf with it, and follow the web site instructions.4 Ways to access the databaseThere are three main ways of accessing data from the MCD which have been implemented to date.Firstly, if you know Fortran, the best way to retrieve environmental data from the Mars climatedatabase at any given locations and times is to use the subroutine mode of the softwaresupplied with the Mars Climate Database. In practice, one only has to call a main subroutine namedcall mcd from within any program written in Fortran. A simple example of such a program(test mcd.F), which can be easily modified, is provided. This mode was developed with particularattention to trajectory simulation applications, but it can also be used for most other purposes.Further information on the use of call mcd are available below.Secondly, users who prefer using IDL, Matlab or Scilab software, or who program in C, C++and/or Python will find examples of how to interface their favorite tools with the Fortran subroutinecall mcd in corresponding subdirectories (see sections 6 to 10). Note that some provided examplesare quite straightforward and brute force approaches; fancier and more efficient couplings withthe MCD are clearly possible.Thirdly, it is possible to access the database directly from within any program written in anyhigh level language or software which can read NetCDF files. This gives some flexibility for particularapplications (e.g. when one wants to handle global fields), although it does demand a muchgreater understanding of how the database contents are organised (see the MCD Detailed DesignDocument for a description), as well as of how the variability models, if these are required, should2 This ”symbolic link” strategy unfortunately does not work with Windows where the full path to the data directorymust be used.6